BOOK XXXI\'. XX. 98-xxii. loi 



in additioii what is called the mould-blend ^ of 

 bronze of a very delicate consistency, because a 

 tenth part of black lead is added and a twentieth of 

 silver-lead ; and this is the best way to give it the 

 colour called Graecanic ' after the Greek.' The 

 last kind is that called pot-bronze, taking its name 

 from the vessels made of it ; it is a blend of three or 

 four pounds of silver-lead with every hundred pounds 

 of copper. The addition of lead to Cyprus copper 

 produces the purple colour seen in the bordered 

 robes of statues. 



XXI. Thinjjs made of copper or bronze get Copper-rusi. 

 covered with copper-rust ^ more quickly when they 



are kept rubbed clean than when they are neglected, 

 unless they are well greased with oil. It is said 

 that the best way of preserving them is to give them 

 a coating of Hquid vegetable pitch. The employment 

 of bronze was a long time ago apphed to securing the 

 perpetuity of monuments, by means of bronze 

 tablets on which records of official enactments are 

 made. 



XXII. Copperores and mines supply medicaments 

 in a variety of ways : inasmuch as in their neighbour- 

 hood all kinds of ulcers are healed with the greatest 

 rapidity ; yet the most beneficial is cadmeaS This • cadmea: 

 is certainly also produced in furnaces where silver is 

 smelted, this kind being whiter and not so heavy, 



but it is by no means to be compared with that from 

 copper. There are however several varieties ; for 

 while the mineral itself '^ from which the metal is made 

 is called cadniea, which is necessary for the fusing 

 process but is of no use for medicine, so again another 

 kind ^ is found in furnaces, which is given a name 

 indicating its origin. It is produced by the thinnest 



